Computer security is fast becoming an important issue. With the proliferation of computers and computer networks into all aspects of business and daily life—financial, medical, education, government, and communications—the concern over secure file access is growing. Using passwords is a common method of providing security. Password protection and/or combination type locks are employed for computer network security, automatic teller machines, telephone banking, calling cards, telephone answering services, houses, and safes. These systems generally require the knowledge of an entry code that has been selected by a user or has been preset.
Preset codes are often forgotten, as users have no reliable method of remembering them. Writing down the codes and storing them in close proximity to an access control device (i.e. the combination lock) results in a secure access control system with a very insecure code. Alternatively, the nuisance of trying several code variations renders the access control system more of a problem than a solution.
Password systems are known to suffer from other disadvantages. Usually, passwords are specified by a user. Most users, being unsophisticated users of security systems, choose passwords that are relatively insecure. As such, many systems protected by passwords are easily accessed through a simple trial and error process.
A security access system that provides substantially secure access and does not require a password or access code is a biometric identification system. A biometric identification system accepts unique biometric information from a user and identifies the user by matching the information against information belonging to registered users of the system. One such biometric identification system is a fingerprint recognition system.
In a fingerprint input transducer or sensor, the finger under investigation is usually pressed against a flat surface, such as a side of a glass plate; the ridge and valley pattern of the finger tip is sensed by a sensing means such as an interrogating light beam.
Various optical devices are known which employ prisms upon which a finger whose print is to be identified is placed. The prism has a first surface upon which a finger is placed, a second surface disposed at an acute angle to the first surface through which the fingerprint is viewed and a third illumination surface through which light is directed into the prism. In some cases, the illumination surface is at an acute angle to the first surface, as seen for example, in U.S. Pat. Nos. 5,187,482 and 5,187,748. In other cases, the illumination surface is parallel to the first surface, as seen for example, in U.S. Pat. Nos. 5,109,427 and 5,233,404. Fingerprint identification devices of this nature are generally used to control the building-access or information-access of individuals to buildings, rooms, and devices such as computer terminals.
U.S. Pat. No. 4,353,056 in the name of Tsikos issued Oct. 5, 1982, discloses an alternative kind of fingerprint sensor that uses a capacitive sensing approach. The described sensor has a two dimensional, row and column, array of capacitors, each comprising a pair of spaced electrodes, carried in a sensing member and covered by an insulating film. The sensors rely upon deformation to the sensing member caused by a finger being placed thereon so as to vary locally the spacing between capacitor electrodes, according to the ridge/trough pattern of the fingerprint, and hence, the capacitance of the capacitors. In one arrangement, the capacitors of each column are connected in series with the columns of capacitors connected in parallel and a voltage is applied across the columns. In another arrangement, a voltage is applied to each individual capacitor in the array. Sensing in the respective two arrangements is accomplished by detecting the change of voltage distribution in the series connected capacitors or by measuring the voltage values of the individual capacitances resulting from local deformation. To achieve this, an individual connection is required from the detection circuit to each capacitor.
Before the advent of computers and imaging devices, research was conducted into fingerprint characterisation and identification. Today, much of the research focus in biometrics has been directed toward improving the input transducer and the quality of the biometric input data. Fingerprint characterisation is well known and can involve many aspects of fingerprint analysis. The analysis of fingerprints is discussed in the following references, which are hereby incorporated by reference:    Xiao Qinghan and Bian Zhaoqi: An approach to Fingerprint Identification By Using the Attributes of Feature Lines of Fingerprint,” IEEE Pattern Recognition, pp 663, 1986;    C. B. Shelman, “Fingerprint Classification—Theory and Application,” Proc. 76 Carnahan Conference on Electronic Crime Countermeasures, 1976;    Feri Pernus, Stanko Kovacic, and Ludvik Gyergyek, “Minutaie Based Fingerprint Registration,” IEEE Pattern Recognition, pp 1380, 1980;    J. A. Ratkovic, F. W. Blackwell, and H. H. Bailey, “Concepts for a Next Generation Automated Fingerprint System,” Proc. 78 Carnahan Conference on Electronic Crime Countermeasures, 1978;    K. Millard, “An approach to the Automatic Retrieval of Latent Fingerprints,” Proc. 75 Carnahan Conference on Electronic Crime Countermeasures, 1975;    Moayer and K. S. Fu, “A Syntactic Approach to Fingerprint Pattern Recognition,” Memo Np. 73-18, Purdue University, School of Electrical Engineering, 1973;    Wegstein, An Automated Fingerprint Identification System, NBS special publication, U.S. Department of Commerce/National Bureau of Standards, ISSN 0083-1883; no. 500-89, 1982;    Moenssens, Andre A., Fingerprint Techniques, Chilton Book Co., 1971; and,    Wegstein and J. F. Rafferty, The LX39 Latent Fingerprint Matcher, NBS special publication, U.S. Department of Commerce/National Bureau of Standards; no. 500-36, 1978.
Though biometric authentication is a secure means of identifying a user, it has not penetrated the marketplace sufficiently to be on most desktops. Further, since most forms of biometric authentication require specialised hardware, market penetration is slow and requires both acceptance of the new hardware and a pressing need.
Typical uses of user authentication include system access, user identification, and access to a secure key database. Often a secure key database is encrypted with a key that is accessible through user authentication or identification.
Key management systems are well known. One such system, by Entrust® Technologies Limited is currently commercially available. Unfortunately, current key management systems are designed for installation on a single computer for use with a single fixed user authorisation method and for portability between computers having a same configuration. As such, implementation of enhanced security through installation of biometric input devices is costly and greatly limits portability of key databases. Password based protection of key databases is undesirable because of the inherent insecure nature of most user selected passwords.
For example, when using Entrust® software to protect a key database, the database is portable on a smart card or on a floppy disk. The portable key database is a duplicate of the existing key database. User authentication for the portable key database is identical to that of the original key database. The implications of this are insignificant when password user authentication is employed; however, when biometric user authentication such as retinal scanning or fingerprint identification are used, the appropriate biometric identification system is required at each location wherein the portable key database is used. Unfortunately, this is often not the case. In order to avoid this problem, organisations employ password access throughout and thereby reduce overall security to facilitate portability.
Alternatively, members of an organisation are not permitted to travel with portable key databases and thereby have reduced mobility and are capable of performing fewer tasks while outside the office. This effectively counters many of the benefits available in the information age.
In the past, a system was provided with a single available security system. Typically, prior art systems require a password. Alternatively, a system could require a password and a biometric, or another predetermined combination of user authorisation information. Unfortunately, passwords are inherently insecure. Further, because of the limited number of workstations equipped with biometric scanners and so forth, it is difficult to implement a system secured with biometrics. It would be advantageous to provide a method of user authorisation that is flexible enough to work on different workstations and to accommodate user needs of different users and at different workstations.
Another known system includes a key server. A key server is a single system that provides keys to individuals upon identification or authorisation. Such a system is useful in large organisations since it permits changing of system access codes without requiring every user to provide their personal key data storage device. Because of the extreme problems associated with losing secure keys, it is essential that a key server be backed up appropriately. Further, it is necessary that the server be available at all times. This is achieved through duplication of servers. Unfortunately, key servers are costly and this makes their implementation problematic in some instances. For example, a company performing a trial of a new user access system such as a fingerprint identification system often purchases and installs only a handful of “test” workstations. Thus, to try out fifty (50) fingerprint scanners with a key server configuration requires two robust key servers having full backup capabilities, a main key server and a duplicate key server, and 50 fingerprint imagers. Since a fingerprint imager is likely to cost less than 10% of the cost of the servers, the additional cost is extremely undesirable. Eliminating a need for a duplicate key server would be highly advantageous.